Biomedical subjects

C Magnac

Publications and source records attributed to C Magnac.

22 records · Page 2Linked to original sources

PubMed1992

Evaluation of residual disease in B-cell chronic lymphocytic leukemia patients in clinical and bone-marrow remission using CD5-CD19 markers and PCR study of gene rearrangements.

We evaluated minimal residual disease (MRD) in 23 CD5 + B-chronic lymphocytic leukemia (CLL) patients who achieved clinico-hematological remission confirmed by bone-marrow biopsy. MRD was evaluated by dual marker analysis flow-cytometry using CD5 and CD19 markers, and by the study of Ig heavy chain gene rearrangements using the fast polymerase chain reaction (PCR). According to our laboratory conditions patients were considered to be in complete phenotypic remission when total CD19+ cells were < 25% and the ratio of CD5 + CD19 + /CD19 + cells was < 25%. According to these strict criteria only 9 of the 23 patients were in complete phenotypic remission. In order to evaluate the sensitivity of the above method, PCR analysis of the configuration of the Ig heavy chain gene region was performed in 12 of these patients. Five of 7 patients in complete phenotypic remission retained a detectable monoclonal rearrangement of the Ig heavy chain gene. For the remaining 5 patients in partial phenotypic remission, only one failed to show a monoclonal band and this is probably explained by the presence of an unusual gene rearrangement. In conclusion, this study suggests that PCR is more sensitive than dual marker flow-cytometry for evaluation of residual disease and that it is indeed possible to achieve complete remission at the molecular level, in B-CLL. Nevertheless, we suggest a word of caution as this was a retrospective study, and samples were not assessed before treatment. Thus the possibility that apparent molecular remission might correspond to unusual gene rearrangements cannot be completely excluded in these cases.

Adult↗

PubMed1990

Platelet antibodies in serum of patients with human immunodeficiency virus (HIV) infection.

Between 10 and 15% of human immunodeficiency virus (HIV) seropositive individuals develop an immune thrombocytopenic purpura; however, the mechanism involved in platelet destruction is not yet established. In the present work, we have analyzed 208 sera from HIV seropositive individuals, including 85 thrombocytopenic patients, for the presence of autoantibodies against platelet proteins by using the Western blot technique. Our results indicate that: (1) antibodies against platelet proteins were found in 8 of 123 (6.5%) nonthrombocytopenic patients, as compared with 17 of 85 (20%) of thrombocytopenic patients (p less than 0.03); (2) these antibodies appeared to be more frequently found in advanced stages of disease (p less than 0.02); (3) the reactivity of positive sera with antigenic determinants implicated several distinct platelet proteins; (4) antigens thus recognized are unrelated to the major membrane glycoproteins IIb and IIIa, as well as absent in vero cells and trypsin-sensitive cells. Such results underscore the difficulties in establishing the mechanisms involved in platelet destruction during HIV infection.

Autoantibodies↗

PubMed1987

Detection of anti-mitochondrial antibodies by ELISA and Western-blot techniques and identification by one and two-dimensional gel electrophoresis of M2 target antigens.

Seven hundred and eleven sera were simultaneously studied by immunofluorescence (IF), complement fixation test (CFT) and ELISA for the detection of anti-mitochondrial antibodies (AMA). One hundred and nineteen of these sera were also studied by Western-blot techniques, while some of them were examined by two-dimensional gel electrophoresis so as to identify the polypeptides recognized by M2 antibodies. The results indicated that: (1) ELISA is a more sensitive technique for detecting type M2 AMA (27 scored positive in 27 primary biliary cirrhosis (PBC), as compared to 21/27 by IF and 16/27 by CFT). (2) Although ELISA appeared to be a promising screening method, some false positive results were observed that necessitated a double confirmation of positive sera by another technique. (3) Western-blot experiments with rat mitochondrial purified preparation indicated that sera from AMA type 2 could recognize eight different polypeptides and that most of them identified 63-60, 48, 44, and 35-33 kD polypeptides, whereas the 54 and 27 kD were less frequently recognized. A trypsin treatment of antigens confirmed the enzyme sensitivity of most of these antigens. These results suggested some heterogeneity among M2 AMA, though this series of PBC was not large enough to relate the heterogeneous pattern noticed in Western-blot to the clinical and histological patterns observed in PBC.

Autoantibodies↗

PubMed1987

Co-localization and secretion of parathyrin of Stannius corpuscles (immunoreactive parathyroid hormone) and of secretory glycoproteins including secretory protein-I in the European eel (Anguilla anguilla L.).

Until recently, teleosts were considered to be devoid of parathyroids. We showed recently that the corpuscles of Stannius, that structurally have features in common with the parathyroid gland, produce a molecule resembling mammalian parathyroid hormone (PTH). We refer to this molecule as parathyrin of corpuscles of Stannius (PCS). Parathyroid secretory protein-I (SP-I) is an acidic glycoprotein, probably identical to adrenal chromogranin A, that is co-stored and co-secreted with PTH. In the present study, PCS was localized in secretory granules of fresh water eels by immunocytochemistry. In addition, several glycoproteins were identified in these granules by periodic acid-Schiff staining and/or concanavalin A lectin binding. One of the glycoproteins that was positive with periodic acid-Schiff, but not with concanavalin A, cross-reacted with antisera to bovine parathyroid secretory protein-I. When the eels were made hypercalcemic by injecting calcium or pituitary extract, there was a coincidental translocation of the PCS, immunoreactive SP-I and the glycoproteins, suggestive that these granules were undergoing exocytosis. Immunoblot analysis of saline extract of the corpuscles of Stannius confirmed that immunoreactive SP-I was present in the tissue. It exhibited a molecular mass of about 55 kDa compared to about 70-80 kDa exhibited by mammalian SP-I when analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis.

Animals↗